Slater used the documents to embarrass Phil Goff, who was then Labour Party leader.

Leaked emails suggest he knew about the contents of the OIA in advance and the request was expedited, even though requests from other media for the document were turned down.

Chief Ombudsman Dame Beverly Wakem has backed Key, after a letter from her office emerged today. The letter referred to a "discussion" with Key about the release of documents to Slater.

Earlier, a letter from former SIS director Warren Tucker had emerged. It said Tucker had informed Key about the release. He then clarified that to say he meant Key's office.

In the second letter, to NewstalkZB and dated October 31, 2011, Wakem referred to Tucker having a "discussion" with Key about the release.

In a conversation Wakem had with Tucker, he had told her he was "prepared to release a statement regarding his discussion with the prime minister", the letter said.

"Ms Wakem is of the view that there is good reason to withhold Dr Tucker's full recollection of his discussion with the prime minister."

Wakem said this afternoon she was "very clear" that the director of security communicated with the offices of the prime minister and the leader of the Opposition on this matter.

"In the letter that was written on my behalf while I was away but which had been discussed with me the word 'discussion' is probably loosely used and may have given rise to an impression that there was a direct approach - there wasn't, and there hasn't been," she told Newstalk ZB.

Key said from time to time he had had discussions with Tucker about the release of OIAs.

"But prior to the release of this one I didn't have any discussions at all. "

He had got back from holiday on July 31 and the discussions about the OIA took place before that.

The release went out on August 2 but there was no discussion between him and Tucker about it.

"He did deal with my office but the claims that have been made ... that there was political interference that's absolutely not true."

Tucker had confirmed to him this morning he understood the law perfectly correctly that requires him to be politically neutral.

Key said Tucker had briefed someone in his office. He would not name the person, but said it was not Jason Ede.

He said he didn't think he was ever told the OIA was going out prior to its release but he knew Goff had been briefed on the Israelis because Tucker had told him that and it was standard procedure.

He said the explanation he had been given for why it was released promptly to Slater was that it had little in it "and Mr Goff was effectively defaming Mr Tucker so it was an issue between the two of them."

Tucker was trying to say he had not been wrong in saying he had briefed Goff.

"I can categorically tell you I was not involved in that process prior to it being released."

He did not have any details and had not asked those in his office about how Slater had known it would be "devastating for Goff" before it was released.

Key repeated the book was a smear from the left, presented in a way to discredit the government.